Question about 1989 Jeep Cherokee

4 Answers

Just converted to new a/c coolant system in my 1989 Jeep Cherokee 4L...air now blows at 48 degrees HOWEVER when I press the gas for more power (highway entrance ramp, long hill) the air stops blowing completely but returns when i let up on the gas...goodyear says engine not creating enough vacuum...problem didn't seem to exist before conversion...any ideas?

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  • 3 more comments 
  • alexbalentin Jun 26, 2009

    don't hear any hissing and checks for vacuum leaks reveal nothing...I do have another intermittent problem that may be related...periodically, when I start the car, the engine will rev at 2500-3000 rpms for minutes on end...sometimes this will stop after 2-3 minutes...other times I have to turn car off and wait before restarting...someone mentioned the IAC valve that is part of the vacuum system as a potential source of the problem...maybe I need to check all vacuum sensors as both problems may related...

  • alexbalentin Jun 26, 2009

    also, someone suggested a possible problem with the check valve that is located in a vacuum line leading from the intake manifold to the vacuum line that goes through the firewall...sound plausible?

  • alexbalentin Jun 26, 2009

    great info...goodyear also says that the engine vacuum pressure (?) should be 18-21 but is registering at 14-15...would this effect the vacuum effect in the a/c?

  • alexbalentin Jun 27, 2009

    yes...blower keeps producing air flow but it is diverted to defrost...

  • alexbalentin Jun 29, 2009

    thank you for the comments

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4 Answers

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  • Jeep Master
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1st 48 degrees is not cold enough, the outlet temp should be at least 38-42, so either the system is overcharged or undercharged (either condition will cuase this), when u converted it did u put in 85% as many ounces as the old system called for, R134 is denser than R12 so it takes less to fill the system
Goodyear is right on the reason the air blows to then defrost outlets (if u check this u will see that this is where the airflow diverts to) when u accelerate, this is caused by a loss of vacuum from the engine, there are a few possibilities for this, one is the AC vacuum reservoir canister under the hood is leaking or the vacuum line to it from the engine is leaking, the others poss causes are the vacuum line to the AC control head in the dash is leaking or restricted, the other poss is that the vacuum mode control switch in the dash AC control is leaking vacuum, but in any case it is a loss of vacuum causing this.

Posted on Jun 26, 2009

  • yadayada
    yadayada Jun 27, 2009

    yes it could.

  • yadayada
    yadayada Jun 27, 2009

    and yes a vacuum check valve can cause this problem as well.

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  • Jeep Master
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The blower keeps blowing but the flow is diverted elsewhere at time of acceleration is this correct.?

Posted on Jun 27, 2009

  • 1 more comment 
  • Mike Butler
    Mike Butler Jun 27, 2009

    There is/should be a check valve in main source line to control panel, which have been known to fail. Have you located the main vacuum line going through firewall to your control panel as of yet?

  • Mike Butler
    Mike Butler Jun 27, 2009

    As far as IAC goes, one easy way to check that is to remove it, spray the pintle (pointed part)& shaft with carb cleaner or throttle body spray cleaner, as well as the hole (port) it came out of & see if it makes any difference. If it cures it for a while , then start to do same again, replace IAC motor.

  • Mike Butler
    Mike Butler Jun 27, 2009

    Have you read other comment about check valve & vacuum line.?

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  • Master
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Conversions from R-12 to R134A won't give the same performance as the compressor you're converting has been designed for R-12 and some drop in performance should be expected. Whenever converting from R-12 to R134A, it's important to completely evacuate the system of R-12. The combination of the two refrigerants will compromise the performance of your Ac system. There's also a possibility, that if the system hasn't been evacuated (by a HVAC machine) the system has improper pressure and will fail on occasion. Test the low side pressure. It should read in the 40-45 psi range. If it's low, it may require more refrigerant. If it tests above 45psi, you may have overfilled it, not only impacting the performance of the system but over time will cause damage to the AC and components. Hope you found this answers your question. Best of luck.
Greg

Posted on Jun 26, 2009

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  • Master
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Make sure the AC plug to the compressor is clean and tight. Make sure the compressor is engaging when it doesn't work.

Let me know what you find.

Your description sounds like a possible compressor failure and it may be beyond your skill set my friend. I also wish to point out that the A/C systems in cars are under high pressure and repairs to the system should be carried out by an experienced technician with certifications.

Your description sounds like a possible compressor failure and it may be beyond your skill set my friend. I also wish to point out that the A/C systems in cars are under high pressure and repairs to the system should be carried out by an experienced technician with certifications.

So far, it's been impossible to find a replacement pulley assembly for my 2000 Jeep Cherokee with a bad a/c pulley bearing. Your best bet is to pull the pulley off the pump and either get the bearing out yourself or have it removed by someone. Give Buffalo Bearings a call (1800-669-8019 (716) 874-1720 Fax (716) 874-3063) and tell them what bearing you have. y.

Posted on Jun 26, 2009

  • mohammed marika thambi
    mohammed marika thambi Jun 26, 2009

    A plenum, in air handling jargon, is the air
    filled space between the heat exchanger(s) and the occupied area that
    is climate controlled. In your example, the plenum should have a drain
    hole at it's lowest point for the condensation from the A/C evaporator
    to be jettisoned or over boarded as it were. Look for a plastic box
    that is mounted up against the fire wall and search for a vent or port
    that may be occluded.

    It sounds like it needs recharged.

    If you were to place cardboard under the car, what section of the engine compartment is the coolant coming from?

    If you were to place cardboard under the car, what section of the engine compartment is the coolant coming from?


  • mohammed marika thambi
    mohammed marika thambi Jun 26, 2009

    Check to make sure no vacuum lines are off under
    the hood. Also, listen for hissing sounds with the engine running that
    would indicate a vacuum leak. Also, check under the dash for the same.
    The vents are actuated by vacuum and if you lost it, you may be stuck
    between settings.






    Your description sounds like a possible
    compressor failure and it may be beyond your skill set my friend. I
    also wish to point out that the A/C systems in cars are under high
    pressure and repairs to the system should be carried out by an
    experienced technician with certifications.





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